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NanoSan - Application of nanoscale zero-valent iron (nZVI)  for in situ remediation of groundwater contaminated by chlorinated solvents

Remediation of groundwater contaminated by chlorinated solvents is a demanding task, since these compounds are present in form of both, dissolved phase and residual or pooled dense non-aqueous phase liquids (DNAPL). Until recently, the usual in situ technology to restore such contaminated groundwater was through permeable reactive barriers (PRB) that employ dechlorination via granular zero-valent iron (ZVI). This technology appears effective in removal of the dissolved contaminant plume. Addressing the contamination source in form of residual or pooled DNAPL trapped in the aquifer matrix remains challenging.

Nanoscale zero-valent iron (nZVI) particles, injected into subsurface in form of slurries, are considered to be a beneficial replacement of PRB practices. This is mostly due to their higher chemical reactivity resulting from the increased reactive surface area compared to that of granular ZVI, and consequently reduced remediation time and costs. Moreover, the nZVI particles application enables treatments of contamination in hardly accessible zones (such as these under existing infrastructure), where the PRB practice is not feasible.

The effectiveness of the nZVI application and transport ability in groundwater remediation depends on (1) nZVI particles properties (dechlorination efficiency, selectivity for chlorinated solvents, reactive lifetime), (2) site-specific parameters (groundwater chemistry, surface chemistry, geologic and hydrogeological conditions) and (3) concentration of chlorinated solvents.

This project focuses on improving nZVI particles properties with respect to sufficient longevity, reactivity, and in-depth understanding of their mobility under hydrogeological conditions typically accounted in coarse-grained, alpine, highly productive porous aquifers and under corresponding water chemical conditions.
Exhaustive characterization of nZVI particles with innovating surface coatings, detailed investigation of degradation efficiency in batch and column experiments, and column studies of their transport under varying hydrogeochemical and hydrogeological conditions encountered in alpine aquifers are all steps we are undertaking in this project.

Ph.D. Student: Susanne Laumann
Supervisor: Thilo Hofmann, Frank von der Kammer, Vesna Micic
PI: Thilo Hofmann
Co-PI: Vesna Micic
Project Partner: Austrian Institute of Technology GmbH (AIT), Health&Environment Department

The project is funded by the Federal Ministry of Agriculture, Forestry, Environment and Water Management (BMLFUW). Management by Kommunalkredit Public Consulting GmbH.

Department of Environmental Geosciences
University of Vienna

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